1. Field of the Invention
This invention relates to a unique foliar fertilizer formulation and method of applying same to field crops, particularly legume crops such as soybean, and cereal grain crops, such as corn (maize). More particularly, this invention relates to foliar fertilizer formulations and methods which provide outstanding increases in yield of field crops.
2. Prior Art
It is known that various alpha-oximino alkanoic acid derivatives are plant growth regulators and can be applied to plants to increase crop yield. For example, U.S. Pat. Nos. 3,873,301 and 4,017,301 describe the use of various nitro-alpha-oximino alkanoic acid derivative for increasing crop yield, and U.S Pat. No. 3,923,491 describes the use of other derivatized alpha-oximino alkanoic acid compounds for increasing crop yield. It is recognized by those skilled in the art that plant growth regulator formulations have inconsistent effects on crop yield. This inconsistency can be attributed to environmental, developmental, and genetic effects as well as other unidentified factors.
In foliar feeding of plants nutrients, the nutrients are dissolved in water and the aqueous solution is sprayed on the leaves of the plants. U.S. Pat. No. 3,087,806 describes a method for improving the yield of soybeans by spraying the plants periodically throughout their growth with an aqueous solution of urea phosphate. The patent recommends twice weekly applications, and in an example such twice weekly sprayings were carried out for a period of 18 weeks.
U.S. Pat. No. 3,558,300 describes a method for foliar feeding of field crops, including soybeans and cereal grains, with an aqueous solution of an ammonium polyphosphate. Adequate ground fertilizer is employed in conjunction with the foliar feeding. It is claimed that the method improves the stress resistance of the plants. The ammonium polyphosphate solution is described as being applied during the crop growth period up to the flowering period.
U.S. Pat. No. 4,038,064 describes a foliar fertilizer composition containing water, urea, potassium, sulfur, phosphorus in the form of linear polyphosphates, and micronutrients, such as sulfur, boron, zinc, iron, manganese and copper. The patent also describes a process of improving soybean plant yields by applying the composition of the foliage of the soybean plant. The patent states that the composition must be applied during the period from shortly before flowering to shortly after the beginning of seed fill.
U.S. Pat. No. 4,146,383 describes a method for improving the yield of legume field crops and cereal grain crops by applying a foliar fertilizer composition containing sources of nitrogen, phosphorus, potassium and sulfur to the foliage of the crops during the seed filling period. The patent specifies that prior to the seed filling period, nutrients are supplied to the growing legume and cereal crops exclusively from the soil.
U.S. Pat. No. 4,033,146 describes a method of fertilizing conifer forests with nitrogen containing compounds by direct aerial application to the conifer foliage of an aqueous solution containing a nitrogen source, such as urea, ammonia, and nitrates of ammonium, calcium and potassium; ammonium phosphates and sulfates; or combinations thereof. The patent states that other micronutrients including iron, manganese, copper and zinc can be added to the solution.
U.S. Pat. No. 4,033,747 discloses a method of fertilizing conifer forest by direct application to the foliage of the conifers a solution containing a water-soluble nitrogen source. The patent also states that the solution may include sources of calcium, potassium, phosphorus, sulfur and minor trace metal nutrients such as iron, cobalt, molybdenum, manganese, copper, boron, zinc, magnesium and mixtures thereof.
It has been reported that mixed results have been achieved with foliar fertilization of crops, especially field crops and more particularly soybeans. While some tests suggested that yield improvements could be achieved, others suggested that no improvements at all were realized from foliar application of nitrogen-phosphorus-potassium (N-P-K) solutions. The January, 1969 issue of World Farming contains a more complete dissertation of the benefits of N-P-K foliar fertilization and the limits of application level beyond which leaf scorch occurs. Another article reprinted from Ohio Farm and Home Research, Vol. 41, No. 302, September-October, 1956, reports no benefit from foliar application of N-P-K solutions.
Unsuccessful attempts to increase yield by foliar fertilization have been reported by Mederski and Volk for wheat, corn, soybeans, oats and alfalfa. When the field crops were grown in soils with adequate fertility they failed to respond positively to foliar sprays containing N, P, and K. (Mederski, H. J. and Volk, G. W. "Foliar Fertilization of Field Crops", Ohio Agr. Exp. Sta. Research Cir 35, August 1956). It has been generally assumed that legume and cereal grain crops which have adequate soil fertilization will not produce significantly higher yeilds of the grain by supplemental foliar fertilization, although it has been recognized that the nutrients in the spray are absorbed by the leaves of the plants.
It was speculated that the adverse results were due to varying environmental factors, soil fertilizes and especially to the inability to apply more than small quantities of foliar fertilizers without damaging plant tissue, especially foliage. Several methods have been proposed for obviating the burning or plasmolysis effects of foliar application of fertilizers. For example, U.S. Pat. Nos. 4,318,729, 3,677,746, and 4,033,745 teach the use of urea formaldehyde polymers to obviate the burning problem by controlled slow release of the nitrogen over an extended period of time. However, these compositions also suffer from several disadvantages. For example, certain of these compositions release nitrogen at such a reduced rate that the growth of the plant and crop yield are not affected to any appreciable extent, and significant amounts of nitrogen remain unreleased at the end of the growing season and is lost.